JP6942496B2 - Zoom lens and imaging device with it - Google Patents

Description

The present invention relates to a zoom lens and is suitable as an image pickup optical system for an image pickup device such as a digital camera, a video camera, a TV camera, a surveillance camera, and a silver salt film camera.

Conventionally, the imaging optical system used for an imaging device (camera) is a zoom lens having a wide angle of view so as to fit a wider range in one image and having high optical performance over the entire zoom range and the entire object distance. Is required. Further, in order to obtain a high-definition image, it is required to have an image blur correction function (vibration isolation function) that suppresses image deterioration due to image blur caused by vibration such as camera shake during imaging.

Conventionally, as a zoom lens that can easily widen the angle of view, a negative lead type zoom lens in which a lens group having a negative refractive power is located on the object side is known (Patent Document 1). In addition, a wide-angle zoom lens that is a negative lead type and has an image blur correction function that corrects image blur by moving a part of the lens of the optical system in the direction having a component in the direction perpendicular to the optical axis is known. (Patent Documents 2 and 3).

In Patent Documents 1 to 3, the lens group is composed of the first lens group to the fourth lens group having negative, positive, negative, and positive refractive powers in order from the object side to the image side, and the four groups for zooming by changing the distance between the lens groups. The zoom lens is disclosed. Of these, in Patent Document 2, the entire third lens group is moved in a direction substantially perpendicular to the optical axis to correct image blur. In Patent Document 3, image blur is corrected by a part of the lens groups of the third lens group, and focusing is performed by a part of the lens groups of the second lens group.

Japanese Unexamined Patent Publication No. 2008-046208 Japanese Unexamined Patent Publication No. 2012-247687 Japanese Unexamined Patent Publication No. 10-039210

A negative lead type zoom lens preceded by a lens group having a negative refractive power is relatively easy to widen the angle of view. However, in a negative lead type zoom lens, when the imaging angle of view is about 100 degrees, it becomes very difficult to correct various aberrations. For example, eccentric aberration often occurs during image blur correction, and it becomes very difficult to obtain high optical performance.

In order to maintain high optical performance with less eccentric aberration during image blur correction while aiming for a wider angle of view with a negative lead type zoom lens, the zoom type and the refractive power (power) of each lens group, etc. It becomes important to set properly. Further, in a negative lead type zoom lens, aberration fluctuation tends to increase during focusing. In order to reduce aberration fluctuations during focusing, it is effective to use a so-called floating method in which two lens groups are moved by different trajectories during focusing.

However, in order to reduce aberration fluctuations during focusing by using the floating method, it is important to appropriately set the lens group to be moved during focusing and the moving direction of the lens group.

The present invention provides a zoom lens having a wide angle of view, less occurrence of eccentric aberration during image blur correction, less aberration fluctuation during focusing, and high optical performance can be easily obtained over the entire zoom range and the entire object distance. The purpose.

The zoom lens of the present invention has a first lens group having a negative refractive force, a second lens group having a positive refractive force, a third lens group having a negative refractive force, and a positive lens group arranged in order from the object side to the image side. A zoom lens consisting of a fourth lens group of refractive power and a rear group including one or more lens groups, and the distance between adjacent lens groups changes during zooming. When focusing from infinity to close range at the wide-angle end. , The second lens group and the third lens group move to the image side, and when focusing from infinity to a close distance at the telephoto end, the second lens group moves to the image side, and the third lens group moves to the object side. Go to, when the image blur compensation, at least a portion of the fourth lens group, wherein the moving direction containing a component in the direction perpendicular to the optical axis.

According to the present invention, there is a zoom lens having a wide angle of view, less occurrence of eccentric aberration during image blur correction, less aberration fluctuation during focusing, and high optical performance can be easily obtained over the entire zoom range and the entire object distance. can get.

Lens cross-sectional view of the zoom lens of Example 1 in the present invention (A) (B) Aberration diagram of the wide-angle end and the telephoto end of the zoom lens of the first embodiment in the present invention when the object distance is infinite. (A) (B) Aberration diagram at the wide-angle end and the telephoto end when the object distance of the zoom lens of Example 1 in the present invention is closest. (A) (B) Lateral aberration diagram at the wide-angle end when there is no shift and at the telephoto end when there is no shift when the object distance of the zoom lens of Example 1 in the present invention is infinite. (C) (D) Horizontal aberration diagram of the zoom lens of Example 1 in the present invention at the wide-angle end at 0.3 degree vibration isolation at infinite object distance and at the telephoto end at 0.3 degree vibration isolation. Lens cross-sectional view of the zoom lens of Example 2 in the present invention (A) (B) Aberration diagram of the wide-angle end and the telephoto end of the zoom lens of the second embodiment of the present invention when the object distance is infinite. (A) (B) Aberration diagram at the wide-angle end and the telephoto end when the object distance of the zoom lens of Example 2 in the present invention is closest. (A) (B) Lateral aberration diagram at the wide-angle end when there is no shift and at the telephoto end when there is no shift when the object distance of the zoom lens of Example 2 in the present invention is infinite. (C) (D) Horizontal aberration diagram of the zoom lens of Example 2 in the present invention at the wide-angle end at 0.3 degree vibration isolation at infinite object distance and at the telephoto end at 0.3 degree vibration isolation. Lens cross-sectional view of the zoom lens of Example 3 in the present invention (A) (B) Aberration diagram of the wide-angle end and the telephoto end of the zoom lens of Example 3 in the present invention at an infinite object distance. (A) (B) Aberration diagram at the wide-angle end and the telephoto end when the object distance of the zoom lens of Example 3 in the present invention is closest. (A) (B) Lateral aberration diagram at the wide-angle end when there is no shift and at the telephoto end when there is no shift when the object distance of the zoom lens of Example 3 in the present invention is infinite. (C) (D) Horizontal aberration diagram of the zoom lens of Example 3 in the present invention at the wide-angle end at 0.3 degree vibration isolation at infinite object distance and at the telephoto end at 0.3 degree vibration isolation. Explanatory drawing of the main part of the image pickup apparatus of this invention

Hereinafter, embodiments of the zoom lens of the present invention and an imaging device having the same will be described with reference to the accompanying drawings.

The zoom lens of the present invention includes a first lens group having a negative refractive power, a second lens group having a positive refractive power, and a third lens group having a negative refractive power arranged in order from the object side to the image side. It is composed of a fourth lens group having an optical power of 1 and a rear group including one or more lens groups. The distance between adjacent lens groups changes during zooming. At least the third lens group moves during focusing, and the lens system IS including a part or the whole of the fourth lens group moves so as to include a component in the direction perpendicular to the optical axis during image blur correction.

FIG. 1 is a cross-sectional view of a zoom lens according to a first embodiment of the present invention at a wide-angle end. 2 (A) and 2 (B) are longitudinal aberration diagrams of the zoom lens of the first embodiment of the present invention at the wide-angle end and the telephoto end when the object distance is infinite. 3 (A) and 3 (B) show the wide-angle end of the zoom lens of the first embodiment of the present invention when the object distance is close (350 mm when the numerical data described later is expressed in mm, the same applies hereinafter in each embodiment). It is a longitudinal aberration diagram at the telephoto end.

4A and 4B show the lateral image of the zoom lens of the first embodiment of the present invention at the time of no shift (reference state) at the wide-angle end at infinite object distance and at the time of image blur correction at the telephoto end when there is no shift. It is an aberration diagram. 4B (C) and 4 (D) are lateral aberration diagrams at the wide-angle end of the zoom lens of Example 1 of the present invention at the time of correction of 0.3 degree image shake and at the telephoto end at the time of correction of 0.3 degree image shake. be. Here, the time of no shift means the time when the image blur correction is not performed.

FIG. 5 is a cross-sectional view of the zoom lens of the second embodiment of the present invention at the wide-angle end. 6 (A) and 6 (B) are longitudinal aberration diagrams of the zoom lens of the second embodiment of the present invention at the wide-angle end and the telephoto end when the object distance is infinite. 7 (A) and 7 (B) are longitudinal aberration diagrams at the wide-angle end and the telephoto end of the zoom lens of the second embodiment of the present invention when the object distance is close.

8A (A) and 8A (B) show laterality of the zoom lens of the second embodiment of the present invention at the time of no shift (reference state) at the wide-angle end when the object distance is infinite and at the time of image blur correction at the telephoto end when there is no shift. It is an aberration diagram. 8B (C) and 8B (D) are lateral aberration diagrams at the wide-angle end of the zoom lens of the second embodiment of the present invention at the time of 0.3 degree image shake correction and at the telephoto end at the time of 0.3 degree image shake correction. be.

FIG. 9 is a cross-sectional view of the zoom lens of the third embodiment of the present invention at the wide-angle end. 10 (A) and 10 (B) are longitudinal aberration diagrams of the zoom lens of the third embodiment of the present invention at the wide-angle end and the telephoto end when the object distance is infinite. 11 (A) and 11 (B) are longitudinal aberration diagrams at the wide-angle end and the telephoto end of the zoom lens of the third embodiment of the present invention when the object distance is close.

12A and 12A (B) show laterality of the zoom lens according to the third embodiment of the present invention at the time of no shift (reference state) at the wide-angle end at infinite object distance and at the time of image blur correction at the telephoto end when there is no shift. It is an aberration diagram. 12B (C) and 12B (D) are lateral aberration diagrams at the wide-angle end of the zoom lens of Example 3 of the present invention at the time of correction of 0.3 degree image shake and at the telephoto end at the time of correction of 0.3 degree image shake. be. FIG. 13 is a schematic view of a main part of the image pickup apparatus of the present invention.

The zoom lens of each embodiment is an imaging optical system (optical system) used in an imaging device such as a video camera, a digital video camera, and a silver salt film camera. In the cross-sectional view of the lens, the left side is the object side (front) and the right side is the image side (rear). In the lens cross-sectional view, i indicates the order of the lens groups from the object side, and Li is the i-th lens group. The LR is a posterior group that includes one or more lens groups. ST is an aperture stop. IS is a lens system for image blur correction.

IP is an image plane, and when used as a shooting optical system for a video camera or digital still camera, it is used on the image pickup surface of a solid-state image sensor (photoelectric conversion element) such as a CCD sensor or CMOS sensor. Corresponds to the film surface. The arrows show the movement trajectory of each lens group during zooming from the wide-angle end to the telephoto end. The arrows Fo and FL related to focus indicate the moving direction of the lens group when focusing from infinity to a short distance. The arrow relating to the image blur correction indicates the moving direction of the lens system IS that moves in the direction including the component in the direction perpendicular to the optical axis during the image blur correction.

Each longitudinal aberration diagram shows spherical aberration, astigmatism, distortion, and chromatic aberration of magnification in order from the left. In the figure showing spherical aberration, the solid line d represents the d line (587.6 nm), and the two-dot broken line g represents the g line (435.8 nm). Further, in the figure showing astigmatism, the solid line S represents the sagittal direction of the d line, and the broken line M represents the meridional direction of the d line. The figure showing the distortion shows the distortion on the d-line. In the figure showing chromatic aberration of magnification, g represents the g line. Fno is an F number. ω is a half angle of view. In the transverse aberration diagram, S represents a sagittal ray and M represents a meridional ray.

In each of the following embodiments, the wide-angle end and the telephoto end refer to the zoom positions when the variable magnification lens group is mechanically located at both ends of a movable range on the optical axis. The above-mentioned Patent Document 1 is a four-group zoom lens composed of a first lens group to a fourth lens group having negative, positive, negative, and positive refractive powers arranged in order from the object side to the image side. As a whole, it is a retrofocus type refractive power arrangement in which a first lens group having a negative refractive power and a composite lens group having a positive refractive power after the second lens group are arranged, and the imaging angle of view exceeds 100 degrees. It is an arrangement of refractive power for ultra-wide angle of view.

Further, when zooming from the wide-angle end to the telephoto end, the short zoom configuration is based on narrowing the distance between the lens group having a negative refractive power and the lens group having a positive refractive power. Dividing the second and subsequent lens groups into positive, negative, and positive refractive power lens groups, and moving the negative refractive power lens group in between to the image side relative to the positive refractive power lens group. So, while performing scaling, aberration correction is performed. In a retrofocus type zoom lens, it is often performed by moving a first lens group in which aberration fluctuation during focusing is relatively small. In recent years, many of them use the inner focus method to perform silent and high-speed focus drive.

For example, when focusing is performed with the second lens group, both the incident height h of the on-axis ray at the telephoto end and the incident height h-of the off-axis main ray at the wide-angle end become large. Therefore, it becomes difficult to correct the aberration fluctuation due to focusing.

Therefore, the present inventor assists the focusing movement of the third lens group having a negative refractive power in addition to the second lens group to cause both fluctuations in curvature of field at the wide-angle end and fluctuations in spherical aberration at the telephoto end. I'm making it smaller. On the other hand, in recent years, a zoom lens having a wide angle of view is required to have an image blur correction function (vibration isolation function). In a 4-group zoom lens consisting of a 1st lens group to a 4th lens group having negative, positive, negative, and positive refractive powers, the effective diameter becomes smaller as described in Patent Document 2 when correcting image blur. It is effective to use a third lens group with a negative refractive power.

This is because the incident height of the off-axis ray is low because it is close to the aperture diaphragm, and the ray is converged by the second lens group having a positive refractive power, and the incident height of the on-axis ray is also low. That is, the third lens group L3 is suitable as both an auxiliary lens group for focusing and a lens group for image blur correction. However, when trying to construct a zoom lens having a wide angle of view, which has a small aberration fluctuation due to a change in the object distance and has an image blur correction function, it becomes difficult to construct these configurations in a compact and simple manner mechanically. Come on.

Therefore, in the present invention, first, the focusing assist is performed by the third lens group having a negative refractive power. Next, the fourth lens group having a positive refractive power is divided into a plurality of lens groups to form a lens group having a positive refractive power (fourth lens group) at a position where the incident height h of the axial ray is higher than that on the object side. It was divided into two lens groups in the rear group, which included a lens group with a weaker refractive power on the image side.

Since the fourth lens group having a positive refractive power is located near the aperture diaphragm, the incident height h-of the off-axis ray is small and the incident height h of the on-axis ray is large, which is suitable for correcting the aberration of the on-axis ray. ing. Further, since the axial light beam that is afocal in the third lens group L3 having a negative refractive power is incident, the effective diameter becomes substantially the same as that of the third lens group L3. In the rear group, the incident height h of the on-axis ray becomes small due to the positive refractive power of the fourth lens group, and the incident height h-of the off-axis ray becomes high at a position away from the aperture diaphragm. Suitable for aberration correction.

With such a refractive power arrangement, the fourth lens group with a positive refractive power with a small effective diameter is used as the lens system IS for image blur correction, and the fourth lens group reduces aberration fluctuations due to object distance and image blur. I am making corrections.

For the above reasons, the zoom lens of the present invention is composed of the following lens groups arranged in order from the object side to the image side. Negative refractive power first lens group L1, positive refractive power second lens group L2, negative refractive power third lens group L3, positive refractive power fourth lens group L4, one or more lenses It is composed of a posterior group LR including a group.

The distance between adjacent lens groups changes during zooming. At the time of focusing, at least the third lens group L3 moves. A part or the whole lens system IS of the fourth lens group L4 moves so as to include a component in the direction perpendicular to the optical axis at the time of image blur correction. That is, vibration isolation is performed. As a result, a zoom lens is obtained in which aberration fluctuations due to fluctuations in the object distance are small and image blur correction can be performed satisfactorily.

Next, a more preferable configuration of the zoom lens of the present invention will be described. At the time of focusing, it is preferable that all or a part of the second lens group L2 moves in addition to the third lens group L3. In the second lens group L2, the incident height h of the axial light beam is high at the telephoto end, and the focusing sensitivity is high. On the other hand, the incident height h− of the off-axis ray is also high at the wide-angle end, and it becomes difficult to suppress the aberration fluctuation during focusing. If the aberration fluctuation at this time is corrected by the focusing movement of the third lens group L3, the focusing and the aberration fluctuation at that time can be corrected most efficiently.

When focusing from infinity to a close distance on the wide-angle end side, it is preferable that the second lens group L2 and the third lens group L3 move to the image side. According to this, the curvature of field generated by the movement of the second lens group L2 can be effectively corrected, which is preferable. Further, when focusing from infinity to a close distance on the telephoto end side, it is preferable that the second lens group L2 moves to the image side and the third lens group L3 moves to the object side. According to this, the fluctuation of the spherical aberration generated by the movement of the second lens group L2 can be effectively corrected, which is preferable.

In each embodiment, the fourth lens group L4 preferably has two positive lenses and one negative lens. The rear group LR has a lens group having a positive refractive power, and the lens group LP of the most object among the lens groups having a positive refractive power included in the rear group LR has two positive lenses and one negative lens. Is good. In Example 1, the rear group LR is composed of a fifth lens group having a positive refractive power. In the second embodiment, the rear group LR is composed of a fifth lens group L5 having a negative refractive power and a sixth lens group L6 having a positive refractive power arranged in order from the object side to the image side.

In the third embodiment, the rear group LR is composed of a fifth lens group L5 having a positive refractive power and a sixth lens group L6 having a negative refractive power arranged in order from the object side to the image side. In each embodiment, it is preferable that one or more of the following conditional expressions are satisfied. Let fRw be the focal length of the rear group LR at the wide-angle end, and fw be the focal length of the entire system at the wide-angle end. The focal length of the lens system IS for image blur correction is f4S. Let the focal length of the first lens group L1 be f1, the focal length of the second lens group L2 be f2, and the focal length of the third lens group L3 be f3.

At this time, it is preferable to satisfy one or more of the following conditional expressions.
−0.1 <fw / fRw <0.3 ・ ・ ・ (1)
2.0 <f4S / fw <6.0 ... (2)
1.0 <−f1 / fw <2.0 ... (3)
1.0 <f2 / fw <3.0 ... (4)
1.0 <-f3 / fw <4.0 ... (5)

Next, the technical meaning of each of the above conditional expressions will be described. The conditional expression (1) relates to the refractive power of the rear group LR. Conditional expression (1) is for effectively obtaining anti-vibration sensitivity while reducing the size of the fourth lens group L4 by appropriately setting the share of the fourth lens group L4 with the positive refractive power. Is. If the upper limit of the conditional expression (1) is exceeded, the positive refractive power of the fourth lens group L4 is weakened, the anti-vibration sensitivity is reduced, and it becomes difficult to effectively correct the image blur. If the lower limit of the conditional expression (1) is exceeded, the incident height h− of the off-axis light beam to the fourth lens group L4 becomes high, so that the effective diameter becomes large and the vibration isolation mechanism becomes large, which is not preferable. ..

The numerical range of the conditional expression (1) is more preferably set as follows.
0.0 <fw / fRw <0.2 ... (1a)
That is, when the refractive power of the rear group LR is positive, the refractive power arrangement of the retrofocus becomes strong, and it becomes easy to widen the angle of view at the wide-angle end, which is preferable.

The conditional expression (2) is for appropriately setting the refractive power of the lens system IS for image blur correction and effectively obtaining the anti-vibration sensitivity. If the upper limit of the conditional expression (2) is exceeded, the anti-vibration sensitivity becomes too low, and the shift amount (movement amount) of the lens system IS at the time of image blur correction becomes large, which is not preferable. If the lower limit of the conditional expression (2) is exceeded, the refractive power of the lens system IS for image blur correction becomes too strong, and vibration isolation control for image blur correction becomes difficult, which is not preferable.

The numerical range of the conditional expression (2) is more preferably set as follows.
2.5 <f4S / fw <5.5 ... (2a)
The conditional equations (3), (4), and (5) optimize the refractive power of each lens group of the first lens group L1, the second lens group L2, and the third lens group L3, while suppressing fluctuations in various aberrations. This is to reduce the size of the entire system.

When the upper limit of the conditional expression (3) is exceeded, the negative refractive power of the first lens group L1 is too weak (the absolute value of the negative refractive power is too small), and the wide-angle end is widened. It will be difficult. When the lower limit of the conditional equation (3) is exceeded, the negative refractive power of the first lens group L1 is too strong (the absolute value of the negative refractive power becomes too large), and the sagittal curvature of field and distortion at the wide-angle end. Aberrations increase, making it difficult to correct these aberrations.

If the upper limit of the conditional expression (4) is exceeded, the positive refractive power of the second lens group L2 is too weak, and it becomes difficult to obtain a sufficient zoom ratio. If the lower limit of the conditional expression (4) is exceeded, the positive refractive power of the second lens group L2 is too strong, and it becomes difficult to correct astigmatism at the telephoto end.

When the upper limit of the conditional expression (5) is exceeded, the negative refractive power of the third lens group L3 is too weak, and a sufficient magnification ratio due to a change in the distance between the second lens group L2 and the third lens group L3 is secured. Becomes difficult. If the lower limit of the conditional expression (5) is exceeded, the negative refractive power of the third lens group L3 is too strong, and spherical aberration is overcorrected at the telephoto end, which is not preferable.

It is preferable to set the numerical range of the conditional expressions (3) to (5) as follows.
1.2 <−f1 / fw <1.8 ... (3a)
1.3 <f2 / fw <2.5 ... (4a)
1.3 <-f3 / fw <3.5 ... (5a)

Next, a preferable configuration will be described in each embodiment. The rear group LR has a lens group having a positive refractive power, and the lens group arranged closest to the object side among the lens groups having a positive refractive power included in the rear group LR is referred to as a lens group LP. When zooming from the wide-angle end to the telephoto end, it is preferable that the distance between the fourth lens group and the lens group LP is narrowed. According to this, there is a gap between the fourth lens group L4 and the lens group LP at the wide-angle end, the incident height h-of the off-axis main ray at the fourth lens group L4 can be reduced, and the lens for image blur correction. It becomes easy to reduce the effective diameter of the system IS.

It is preferable that the fourth lens group L2 has two positive lenses and one negative lens. In order to correct the aberration (vibration-proof aberration) at the time of image blur correction, it is preferable to have a lens having a different sign instead of a single lens, and in order to effectively obtain a positive refractive power, it is better than a negative lens. It is also preferable to increase the number of positive lenses. In particular, it is preferable that the fourth lens group L4 is composed of three lenses, two positive lenses and one negative lens, in order to reduce the size of the entire system.

It is preferable that the lens group LP has two positive lenses and one negative lens. In order to satisfactorily correct off-axis aberrations, it is preferable to have a lens having a different sign instead of a single lens, and in order to effectively obtain a positive refractive power, the number of lenses of a positive lens is larger than that of a negative lens. It is preferable to increase the number. When zooming from the wide-angle end to the telephoto end, the distance between the first lens group L1 and the second lens group L2 is narrowed, the distance between the second lens group L2 and the third lens group L3 is widened, and the distance between the third lens group L3 and the fourth lens is widened. It is preferable that the interval between the groups L4 is narrowed.

As the zoom lens of the present invention, for example, a five-group zoom lens composed of a first lens group L1 to a fifth lens group L5 having negative, positive, negative, positive, and positive refractive powers can be applied in order from the object side. In addition, a 6-group zoom lens consisting of the 1st lens group L1 to the 6th lens group L6 with negative, positive, negative, positive, negative, and positive refractive power, and negative, positive, negative, positive, positive, and negative refraction. A 6-group zoom lens or the like composed of the first lens group L1 to the sixth lens group L6 of power can be applied.

Here, the lens group means that the distance between the frontmost surface of the optical system or the lens adjacent to the front surface changes by zooming, and the distance between the rearmost surface of the optical system or the lens adjacent to the rear side changes by zooming. Say up to the side to do.

Hereinafter, the configuration in each embodiment will be described. The first embodiment is composed of the following lens groups arranged in order from the object side to the image side. Negative power first lens group L1, positive power second lens group L2, negative power third lens group L3, positive power fourth lens group L4, positive power first It is composed of 5 lens groups L5 (lens group LP). This is a 5-group zoom lens with an imaging angle of view of 102.38 degrees at the wide-angle end and a zoom ratio of 3.91.

At the time of focusing, the second lens group L2 moves to the image side in the entire zoom range, and the focusing sensitivity is effectively obtained. Further, during focusing, the third lens group L3 moves toward the image side near the wide-angle end and toward the object side near the telephoto end. As a result, fluctuations in curvature of field are corrected on the wide-angle side and fluctuations in spherical aberration are corrected on the telephoto side.

The lens system IS for image blur correction includes a fourth lens group L4. By satisfying the conditional equations (1) and (2), the fourth lens group L4 and the fifth lens group L5 suppress the increase in the effective diameter of the fourth lens group L4, and the axial light beam in the fourth lens group L4. The aberration of the off-axis light beam is effectively corrected by the fifth lens group L5.

When zooming from the wide-angle end to the telephoto end, the distance between the 4th lens group L4 and the 5th lens group L5 is narrowed, so that the axes of the 4th lens group L4 and the 5th lens group L5 are narrowed at the wide-angle end. The difference in the incident height h-of the external light is increased, facilitating the reduction in diameter. Further, when zooming from the wide-angle end to the telephoto end, the distance between the first lens group L1 and the second lens group L2 is narrowed, the distance between the second lens group L2 and the third lens group L3 is widened, and the third lens group L3 By narrowing the distance between the fourth lens group L4, scaling is effectively performed.

Further, the 4th lens group L4 and the 5th lens group L5 are both composed of two positive lenses and one negative lens, and while maintaining miniaturization, the fourth lens group L4 reduces eccentric aberration. However, in the fifth lens group L5, off-axis aberration is effectively suppressed. Further, the first lens group L1, the second lens group L2, and the third lens group L3 satisfy the conditional expressions (3), (4), and (5), respectively, thereby reducing the size of the entire system. At the same time, it has obtained high optical performance.

The second embodiment is composed of the following lens groups arranged in order from the object side to the image side. Negative refractive power first lens group L1, positive refractive power second lens group L2, negative refractive power third lens group L3, positive refractive power fourth lens group L4, negative refractive power first It is composed of 5 lens groups L5 and a 6th lens group L6 (lens group LP) having a positive refractive power. It is a 6-group zoom lens with an imaging angle of view of 102.38 degrees at the wide-angle end and a zoom ratio of 3.91 times.

When zooming from the wide-angle end to the telephoto end, the distance between the 4th lens group L4 and the 6th lens group L6 is narrowed, so that the 4th lens group L4 and the 6th lens group L6 are moved at the wide-angle end. The difference in the incident height h− of the off-axis light beam is increased, and the diameter of the entire system can be easily reduced. The configuration and optical action of each lens group in Example 2 are the same as those in Example 1.

Example 3 is composed of the following lens groups arranged in order from the object side to the image side. Negative refractive power first lens group L1, positive refractive power second lens group L2, negative refractive power third lens group L3, positive refractive power fourth lens group L4, positive refractive power first It is composed of five lens groups L5 (lens group LP) and a sixth lens group L6 having a negative refractive power. The imaging angle of view at the wide-angle end is 106.02 degrees, and it is a 6-group zoom lens with a zoom ratio of 3.56. The configuration and optical action of each lens group in Example 3 are the same as those in Example 1.

Next, an example in which the zoom lens shown in Examples 1 to 3 is applied to the image pickup apparatus will be described with reference to FIG. FIG. 13 is a schematic view of a main part of the single-lens reflex camera. In FIG. 13, reference numeral 10 denotes an imaging optical system having the zoom lenses 1 of Examples 1 to 3. The zoom lens 1 is held by a lens barrel 2 which is a holding member. Reference numeral 20 denotes a camera body, which is composed of a quick return mirror 3 that reflects a light beam from the imaging optical system 10 upward, and a focal plate 4 arranged in an image forming apparatus of the imaging optical system 10.

Further, it is composed of a pentadha prism 5 that converts an inverted image formed on the focal plate 4 into an erect image, an eyepiece 6 for observing the erect image, and the like. Reference numeral 7 denotes a photosensitive surface, on which a solid-state image sensor (photoelectric conversion element) or a silver salt film that receives an image formed by a zoom lens such as a CCD sensor or a CMOS sensor is arranged. At the time of shooting, the quick return mirror 3 retracts from the optical path, and an image is formed on the photosensitive surface 7 by the shooting lens 10.

The benefits described in Examples 1 to 3 are effectively enjoyed in the imaging apparatus as disclosed in this Example. The same applies to a mirrorless single-lens reflex camera that does not have a quick return mirror 3 as an imaging device.

Although examples of the preferred imaging optical system of the present invention have been described above, it goes without saying that the present invention is not limited to these examples, and various modifications and changes can be made within the scope of the gist thereof.

Numerical data 1 to 3 corresponding to Examples 1 to 3 are shown below. In each numerical data, i indicates the order of the surfaces from the object side. In the numerical data, ri is the radius of curvature of the i-th lens surface in order from the object side, di is the i-th lens thickness and air spacing in order from the object side, and ndi and νdi are the i-th lenses in order from the object side. The refractive index and Abbe number of the material. BF is the back focus. The total length of the lens is the distance from the first lens surface to the final lens surface plus the back focus value.

The aspherical shape is the X-axis in the optical axis direction, the H-axis in the direction perpendicular to the optical axis, the direction of light travel is positive, r is the radius of curvature of the near axis, k is the conical constant, and each aspherical coefficient is A4, A6, A8. , A10, A12,

It shall be given in. “E ± xx” in each aspherical coefficient means “× 10 ^{± xx} ”. Each aspherical surface is indicated by a "*" mark on the right side of the surface number in the surface data.

R13 and r20 in each numerical data are dummy surfaces used in the design. Table 1 shows the relationship between each of the above conditional expressions and the numerical data.

(Numerical data 1)

Unit mm

Surface data Surface number rd nd νd Effective diameter
1 * 1082.538 2.50 1.88300 40.8 57.50
2 22.895 14.52 40.83
3 * -48.107 2.00 1.58313 59.4 40.78
4 * 319.118 0.52 40.08
5 45.216 4.05 1.85478 24.8 40.30
6 100.401 (variable) 39.79
7 * 41.193 2.40 1.76385 48.5 24.70
8 142.453 1.10 1.85478 24.8 24.18
9 31.969 3.43 1.60311 60.6 23.05
10 -384.344 0.15 22.69
11 44.048 3.25 1.76385 48.5 22.59
12 -82.325 (variable) 22.50
13 ∞ 1.00 18.62
14 241.786 0.80 1.77250 49.6 17.48
15 29.322 2.51 16.47
16 -35.973 0.80 1.69680 55.5 16.26
17 28.446 2.88 1.84666 23.8 16.58
18 -240.753 (variable) 16.78
19 (Aperture) ∞ (Variable) 17.11
20 ∞ (variable) 17.56
21 32.886 5.14 1.43875 94.9 18.04
22 -21.947 0.15 18.06
23 -44.992 4.14 1.56732 42.8 17.71
24 -14.266 1.10 1.85026 32.3 17.89
25 -64.960 (variable) 19.05
26 38.105 5.59 1.49700 81.5 22.57
27 -32.233 0.15 22.82
28 -92.171 1.40 1.91082 35.3 22.55
29 26.230 4.09 1.78472 25.7 22.68
30 * 110.219 22.91

Aspherical data first surface
K = 0.00000e + 000 A 4 = 1.72478e-005 A 6 = -3.45899e-008 A 8 = 4.50788e-011 A10 = -3.27350e-014 A12 = 1.02158e-017

Third side
K = 0.00000e + 000 A 4 = 2.19296e-005 A 6 = 2.34566e-008 A 8 = -1.51995e-010 A10 = 1.41757e-013

4th side
K = 0.00000e + 000 A 4 = 3.10095e-005 A 6 = 3.98058e-009 A 8 = -2.25553e-010 A10 = 3.11124e-013 A12 = -7.83414e-017

7th page
K = 0.00000e + 000 A 4 = -6.02960e-006 A 6 = 6.86222e-009 A 8 = -7.64620e-011 A10 = 1.87577e-013

30th page
K = 0.00000e + 000 A 4 = 1.52401e-005 A 6 = 1.16486e-008 A 8 = -4.85550e-011 A10 = 3.85095e-013

Various data Zoom ratio 3.91

Wide-angle medium telephoto focal length 17.40 35.00 67.98
F number 3.23 4.10 5.85
Half angle of view (degrees) 51.19 31.73 17.65
Image height 21.64 21.64 21.64
Lens overall length 168.46 152.31 168.39
BF 38.38 53.37 84.83

d 6 38.98 11.93 1.23
d12 1.50 8.17 14.71
d18 12.54 10.50 1.35
d19 1.00 1.15 1.80
d20 7.00 0.00 0.00
d25 5.39 3.52 0.80

Zoom lens group Data group Start surface Focal length Lens configuration length Front principal point position Rear principal point position
1 1 -23.36 23.59 2.50 -16.60
2 7 26.68 10.33 3.24 -3.13
3 13 -29.49 7.99 1.98 -4.02
4 21 69.51 10.53 -0.64 -7.51
5 26 134.38 11.23 -6.97 -13.18

(Numerical data 2)

Unit mm

Surface data Surface number rd nd νd Effective diameter
1 * 15601.425 2.50 1.88300 40.8 57.84
2 22.927 14.52 40.85
3 * -49.062 2.00 1.58313 59.4 40.78
4 * 359.739 0.21 40.22
5 45.800 4.07 1.85478 24.8 40.45
6 104.042 (variable) 39.95
7 * 43.399 2.34 1.76385 48.5 24.63
8 119.609 1.10 1.85478 24.8 24.06
9 31.702 3.66 1.60311 60.6 22.95
10 -301.786 0.15 22.73
11 41.661 3.60 1.76385 48.5 22.42
12 -80.663 (variable) 22.27
13 ∞ 1.00 17.51
14 -1227.899 0.80 1.77250 49.6 16.28
15 31.173 2.34 15.91
16 -39.901 0.80 1.69680 55.5 15.94
17 28.311 2.92 1.84666 23.8 16.50
18 -179.014 (variable) 16.70
19 (Aperture) ∞ (Variable) 16.49
20 ∞ (variable) 17.23
21 34.210 4.81 1.43875 94.9 17.41
22 -22.290 0.15 17.40
23 -47.218 3.90 1.56732 42.8 16.99
24 -14.789 1.10 1.85026 32.3 16.96
25 -45.788 (variable) 17.72
26 -61.667 1.00 1.84666 23.8 18.09
27 2656.197 (variable) 18.62
28 29.750 5.34 1.49700 81.5 22.08
29 -44.557 0.15 22.37
30 712.118 1.40 1.91082 35.3 22.35
31 19.346 4.88 1.78472 25.7 22.25
32 * 83.456 22.43

Aspherical data first surface
K = 0.00000e + 000 A 4 = 1.70800e-005 A 6 = -3.44155e-008 A 8 = 4.53701e-011 A10 = -3.26163e-014 A12 = 9.94081e-018

Third side
K = 0.00000e + 000 A 4 = 2.22219e-005 A 6 = 2.37055e-008 A 8 = -1.55335e-010 A10 = 1.39414e-013

4th side
K = 0.00000e + 000 A 4 = 3.07204e-005 A 6 = 4.00756e-009 A 8 = -2.24106e-010 A10 = 3.11696e-013 A12 = -8.42451e-017

7th page
K = 0.00000e + 000 A 4 = -5.78948e-006 A 6 = 6.56533e-009 A 8 = -7.64738e-011 A10 = 1.86535e-013

32nd page
K = 0.00000e + 000 A 4 = 1.56394e-005 A 6 = 1.05029e-008 A 8 = 2.39788e-011 A10 = 8.06022e-014

Various data Zoom ratio 3.91

Wide-angle medium telephoto focal length 17.40 35.00 68.00
F number 3.33 4.24 6.03
Half angle of view (degrees) 51.19 31.72 17.65
Image height 21.64 21.64 21.64
Lens overall length 168.42 153.33 168.42
BF 38.34 53.18 83.69

d 6 39.99 12.25 1.00
d12 1.50 7.54 14.08
d18 12.67 9.81 1.31
d19 0.42 1.18 1.80
d20 7.00 0.00 0.00
d25 0.80 1.03 1.00
d27 2.96 3.59 0.80

Zoom lens group Data group Start surface Focal length Lens configuration length Front principal point position Rear principal point position
1 1 -23.27 23.29 2.37 -16.43
2 7 26.24 10.85 3.52 -3.18
3 13 -30.48 7.86 1.59 -4.29
4 21 50.81 9.96 1.66 -5.07
5 26 -71.17 1.00 0.01 -0.53
6 28 69.48 11.77 -3.54 -10.13

(Numerical data 3)

Unit mm

Surface data Surface number rd nd νd Effective diameter
1 * 1084.469 2.50 1.88300 40.8 56.21
2 21.813 14.52 39.24
3 * -48.199 2.00 1.58313 59.4 39.16
4 * 561.232 2.81 38.75
5 51.960 4.09 1.85478 24.8 38.69
6 213.703 (variable) 38.25
7 * 40.774 2.12 1.76385 48.5 20.17
8 166.001 1.10 1.85478 24.8 20.11
9 34.376 3.16 1.60311 60.6 20.00
10 -107.825 0.15 20.07
11 601.187 1.96 1.76385 48.5 20.06
12 -75.283 (variable) 20.03
13 ∞ 1.00 17.60
14 -99.694 0.80 1.77250 49.6 17.39
15 200.761 1.58 17.23
16 -40.224 0.80 1.69680 55.5 17.17
17 27.028 3.00 1.84666 23.8 17.58
18 -846.135 (variable) 17.74
19 (Aperture) ∞ (Variable) 17.69
20 ∞ (variable) 18.31
21 35.591 5.96 1.43875 94.9 18.53
22 -22.048 0.15 18.64
23 -52.502 4.57 1.56732 42.8 18.26
24 -14.145 1.10 1.85026 32.3 18.35
25 -76.958 (variable) 19.58
26 35.779 5.76 1.49700 81.5 22.45
27 -30.590 (variable) 22.63
28 -94.603 1.40 1.91082 35.3 22.05
29 24.777 3.84 1.78472 25.7 21.97
30 * 78.225 22.09

Aspherical data first surface
K = 0.00000e + 000 A 4 = 1.82387e-005 A 6 = -3.59579e-008 A 8 = 4.56631e-011 A10 = -3.17843e-014 A12 = 9.48005e-018

Third side
K = 0.00000e + 000 A 4 = 2.10364e-005 A 6 = 2.19620e-008 A 8 = -1.46769e-010 A10 = 1.16028e-013

4th side
K = 0.00000e + 000 A 4 = 3.05338e-005 A 6 = -3.23851e-010 A 8 = -2.35501e-010 A10 = 3.18960e-013 A12 = -7.73326e-017

7th page
K = 0.00000e + 000 A 4 = -3.85934e-006 A 6 = 8.83188e-009 A 8 = -1.32403e-010 A10 = 4.41636e-013

30th page
K = 0.00000e + 000 A 4 = 1.98233e-005 A 6 = 2.57991e-008 A 8 = -7.68344e-011 A10 = 5.66997e-013

Various data Zoom ratio 3.56

Wide-angle medium telephoto focal length 16.30 35.10 58.00
F number 3.23 4.28 5.99
Half angle of view (degrees) 53.01 31.65 20.46
Image height 21.64 21.64 21.64
Lens overall length 168.43 153.18 168.42
BF 38.25 55.24 83.36

d 6 46.87 11.51 1.00
d12 1.50 11.22 14.10
d18 3.22 6.13 1.45
d19 3.31 2.15 1.80
d20 7.00 0.00 0.00
d25 3.14 1.35 0.80
d27 0.80 1.23 1.56

Zoom lens group Data group Start surface Focal length Lens configuration length Front principal point position Rear principal point position
1 1 -26.31 25.91 0.28 -23.28
2 7 35.74 8.48 2.31 -2.90
3 13 -44.46 7.18 1.83 -3.29
4 21 76.46 11.77 -1.53 -9.09
5 26 34.17 5.76 2.14 -1.83
6 28 -39.72 5.24 1.30 -1.54

L1 1st lens group L2 2nd lens group L3 3rd lens group L4 4th lens group L5 5th lens group LR rear group Fo focus lens group FL focus lens group IS lens system for image blur correction

Claims (13)

A first lens group with a negative refractive power, a second lens group with a positive refractive power, a third lens group with a negative refractive power, and a fourth lens group with a positive refractive power arranged in order from the object side to the image side. A zoom lens composed of a rear group including one or more lens groups, and the distance between adjacent lens groups changes during zooming.
When focusing from infinity to a close distance at the wide-angle end , the second lens group and the third lens group move toward the image side.
When focusing from infinity to a close distance at the telephoto end, the second lens group moves to the image side, and the third lens group moves to the object side.
In the image blur compensation, the zoom lens, which comprises moving in a direction including the component perpendicular least partially on the optical axis of the fourth lens group. When the focal length of the rear group at the wide-angle end is fRw and the focal length of the entire system at the wide-angle end is fw.
-0.1 <fw / fRw <0.3
The zoom lens according to claim 1, wherein the zoom lens satisfies the conditional expression. When the focal length of the moving portion in the fourth lens group for image blur correction is f4S and the focal length of the entire system at the wide-angle end is fw.
2.0 <f4S / fw <6.0
The zoom lens according to claim 1 or 2 , wherein the zoom lens satisfies the conditional expression. When the focal length of the first lens group is f1 and the focal length of the entire system at the wide-angle end is fw,
1.0 <-f1 / fw <2.0
The zoom lens according to any one of claims 1 to 3 , wherein the zoom lens satisfies the conditional expression. When the focal length of the second lens group is f2 and the focal length of the entire system at the wide-angle end is fw,
1.0 <f2 / fw <3.0
The zoom lens according to any one of claims 1 to 4 , wherein the zoom lens satisfies the conditional expression. When the focal length of the third lens group is f3 and the focal length of the entire system at the wide-angle end is fw,
1.0 <-f3 / fw <4.0
The zoom lens according to any one of claims 1 to 5 , wherein the zoom lens satisfies the conditional expression. When zooming from the wide-angle end to the telephoto end, the distance between the lens group arranged on the object side of the positive refractive power lens group included in the rear group and the fourth lens group is narrowed. The zoom lens according to any one of claims 1 to 6. The zoom lens according to any one of claims 1 to 7 , wherein the fourth lens group has two positive lenses and one negative lens. The lens group of the positive refractive power lens group included in the rear group, which is arranged on the object side most, has two positive lenses and one negative lens, according to claims 1 to 8 . The zoom lens according to any one item. The zoom lens according to any one of claims 1 to 9 , wherein the rear group is composed of a fifth lens group having a positive refractive power. Said rear group arranged in order from the object side to the image side, a fifth lens unit having a negative refractive power, according to claim 1 1, characterized in that it is composed of a sixth lens unit having a positive refractive power 0 The zoom lens according to any one of the above. Said rear group arranged in this order from the object side to the image side, a fifth lens unit having positive refractive power, according to claim 1 to 1 1, characterized in that it is composed of a sixth lens unit having a negative refractive power The zoom lens according to any one of the above. A zoom lens according to any one of claims 1 to 1 2, an imaging apparatus characterized by having an image pickup device which receives an image formed by the zoom lens.

Images